Power electronic modules are semiconductor packages that are used in power electronic circuits. Power electronic modules are typically used in vehicular and industrial applications, such as in inverters and rectifiers. The semiconductor components included within the power electronic modules are typically insulated gate bipolar transistor (IGBT) semiconductor chips or metal-oxide-semiconductor field effect transistor (MOSFET) semiconductor chips. The IGBT and MOSFET semiconductor chips have varying voltage and current ratings. The semiconductor components included within the power electronic modules may also include diodes, thyristors, junction gate field-effect transistors (JFETs), and bipolar transistors. Both passive components and control electronics may be included within the power electronic modules. The semiconductor components are made from Si, SiC, GaN, GaAs, or other suitable substrates. Some power electronic modules include additional semiconductor diodes (i.e., free-wheeling diodes) in the semiconductor package for overvoltage protection.
In general, two different power electronic module designs are used. One design is for higher power applications and the other design is for lower power applications. For higher power applications, a power electronic module typically includes several semiconductor chips integrated on a single substrate. The substrate typically includes an insulating ceramic substrate, such as Al2O3, AlN, Si3N4, or other suitable material, to insulate the power electronic module. At least the top side of the ceramic substrate is metallized with either pure or plated Cu, Al, or other suitable material to provide electrical and mechanical contacts for the semiconductor chips. The metal layer is typically bonded to the ceramic substrate using a direct copper bonding (DCB) process, a direct aluminum bonding process (DAB) process, or an active metal brazing (AMB) process.
Typically, soft soldering with Sn—Pb, Sn—Ag, Sn—Ag—Cu, or another suitable solder alloy is used for joining a semiconductor chip to a metallized ceramic substrate. Typically, several substrates are combined onto a planar metal base plate. In this case, the backside of the ceramic substrate is also metallized with either pure or plated Cu, Al, or other suitable material for joining the substrates to the planar metal base plate. To join the substrates to the planar metal base plate, soft soldering with Sn—Pb, Sn—Ag, Sn—Ag—Cu, or another suitable solder alloy is typically used. The planar metal base plate may in turn be attached to a cooling element through which a coolant may flow to prevent overheating of the power electronic module during operation.
With the increasing desire to use power electronics in harsh environments (e.g., automotive applications) and the ongoing integration of semiconductor chips, the externally and internally dissipated heat continues to increase. Therefore, there is a growing demand for high temperature power electronic modules capable of operating with internal and external temperatures up to and exceeding 200° C. In addition, the current density of power electronics continues to increase, which leads to an increase in the density of power losses. Therefore, liquid cooling of the power electronics via cooling elements to prevent overheating is becoming increasingly important.
For these and other reasons, there is a need for the present invention.